The proliferation of the Internet, portable communication devices and wireless networks has lead to the widespread use of communication devices capable of transmitting data as well as voice signals over the air. Most of the communication devices being manufactured provide at least two different wireless technologies to transmit the data; Wireless Wide Area Network (WWAN) technology and Wireless Local Area Network (WLAN) technology.
An example of a WWAN is cellular technology. Initially cellular service providers provided different data packet radio technology depending on the infrastructure they had already established. For example, cellular service providers running on a Code Division Multiple Access (CDMA) infrastructure introduced Evolution-Data Optimized (EV-DO) to provide data packet transfer. Cellular providers running on a Global System for Mobile Communications (GSM) infrastructure introduced General Packet Radio Service (GPRS) to provide data packet transfer. Currently, the GSM and CDMA infrastructures are running 3G standards. However, as the technology evolves, it appears as if most cellular service providers are moving towards the fourth generation of radio technologies, referred to as Long Term Evolution (LTE). It is expected the cellular technologies will continue to advance and evolve. However, cellular technology is still in its relative infancy and access to bandwidth is still relatively expensive and slow.
An example of a WLAN is Wi-Fi, which was developed by the Wi-Fi Alliance. Wi-Fi allows local area networks (LANs) to be deployed without wires for client devices, typically reducing the costs of network deployment and expansion. Spaces where cables cannot be run, such as outdoor areas and historical buildings, can host WLANs. Therefore, portable devices such as notebook computers, video game consoles, mobile phones and personal digital assistants can connect to the Internet when within range of a WLAN connected to the Internet. Using Wi-Fi typically provides relatively inexpensive access to bandwidth. However, Wi-Fi networks have limited range.
Accordingly, performance of the communication device can be improved by enabling it to communicate using multiple communication interfaces, including WWAN and WLAN, at the same time. Thus, the bandwidth available to the communication device is increased when compared to using only one communication interface at a time. An example of such a solution is described in PCT Publication Number WO/2010/063119 titled “MULTI-TRANSPORT MODE DEVICES HAVING IMPROVED DATA THROUGHPUT”.
Applications executing on the communication device use a reliable protocol, such as Transmission Control Protocol (TCP), to communicate data packets, to a server. One of the benefits of using TCP is that it can automatically detect problems and adjust its transmission rate accordingly. For example, traditional TCP implements a network congestion algorithm that reduces the transmission rate when it detects dropped data packets. As the transmission continues without dropping data packets, the transmission rate slowly increases until the maximum rate or the next dropped packets are detected.
While TCP works well for wired networks, over wireless networks data packets are often dropped for reasons other than network congestion. Regardless, however, this drop of data packets will result in the invocation of the TCP congestion control algorithm, even though there may be no congestion on the network. This results in an unnecessary slow down in the transfer of the data packets, which is undesirable.
In order to overcome this problem, a scheme referred to as indirect TCP has been proposed, and is described in Ajay Bakre and B. R. Badrinath, “I-TCP: Indirect TCP for mobile hosts, 1995”. However, the indirect TCP solution is proposed for wireless communication over a single communication interface. For communication devices that communicate over a plurality of different communication interfaces, indirect TCP is inadequate as it does not allow data to be transmitted using multiple interfaces in parallel.
Accordingly, it is an object of the present invention to obviate or mitigate at least some of the above mentioned disadvantages.